Mirror device

Abstract

To provide a mirror device capable of suppressing both of deflection of a mirror section and damage to a movable section.SOLUTION: A mirror device has: a base; a frame-like support section; a movable section in which a mirror surface is formed; a first torsion bar for connecting the movable section to the support section such that the movable section can be rocked with a first axis as a center line; and a second torsion bar for connecting the support section to the base such that the support section can be rocked with a second axis as a center line. In the support section, first beam structure is provided. The first beam structure has: a first part that is formed in a part connected to the first torsion bar in the support section and extends in a direction along the second axis; and a second section that is formed in a part connected to the second torsion bar in the support section and extends in a direction along the first axis. The width of the first part in a direction along the first axis is smaller than the width of the second section in a direction along the second axis.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present disclosure relates to a mirror device configured as, for example, a MEMS (Micro Electro Mechanical Systems) device.

Background Art

[0002] As a MEMS device, a mirror device is known that includes a support portion, a movable portion provided with a mirror portion, and a pair of torsion bars that connect the movable portion to the support portion so that the movable portion can swing about a predetermined axis as a center line. In such a mirror device, in order to suppress the bending of the mirror portion when the movable portion is swung at high speed (for example, at the resonance frequency level (several kHz to several tens of kHz) of the movable portion), in the movable portion, the mirror portion may be connected to a frame-shaped frame via a pair of connecting portions arranged on the above axis (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the mirror device as described above, since the pair of torsion bars and the pair of connecting portions are arranged on the same axis, when the movable portion is swung at high speed, the stress generated in the pair of connecting portions due to the torsion of the pair of torsion bars increases, and there is a risk that the movable portion may be damaged at the connecting portion.

[0005] An object of the present disclosure is to provide a mirror device capable of suppressing both bending of the mirror portion and breakage of the movable portion.

Means for Solving the Problems

[0006] A mirror device according to an aspect of the present disclosure includes a support portion, a movable portion, and a pair of torsion bars disposed on both sides of the movable portion on a first axis and connecting the movable portion to the support portion so that the movable portion can swing about the first axis as a center line. The movable portion has a frame-shaped frame to which the pair of torsion bars are connected and a mirror portion disposed inside the frame. The mirror portion is connected to the frame at each of a pair of first connection regions located on both sides of the mirror portion in a direction parallel to a second axis perpendicular to the first axis. The regions other than the pair of first connection regions in the region between the mirror portion and the frame are spaces. The outer edge of the mirror portion and the inner edge of the frame are connected so that the curvature is continuous at each of the pair of first connection regions when viewed from a direction perpendicular to the first axis and the second axis.

[0007] In this mirror device, a pair of torsion bars connected to the frame-shaped frame are disposed on the first axis, and a pair of first connection regions where the mirror portion and the frame-shaped frame are connected to each other are located on both sides of the mirror portion in a direction parallel to a second axis perpendicular to the first axis. As a result, even if the movable portion is swung at high speed, for example, compared to the case where only the pair of connection regions are located on the first axis or the case where the mirror portion and the frame-shaped frame are connected to each other only in one connection region, the stress generated in each of the pair of first connection regions due to the torsion of the pair of torsion bars is reduced. Further, in this mirror device, the outer edge of the mirror portion and the inner edge of the frame are connected so that the curvature is continuous at each of the pair of first connection regions when viewed from a direction perpendicular to the first axis and the second axis. As a result, stress concentration is less likely to occur in each of the pair of first connection regions. As described above, according to this mirror device, both bending of the mirror portion and breakage of the movable portion can be suppressed.

[0008] The mirror device according to one aspect of the present disclosure includes a support portion, a movable portion, and a pair of torsion bars disposed on both sides of the movable portion on a first axis and connecting the movable portion to the support portion so that the movable portion can swing about the first axis as a center line. The movable portion has a frame-shaped frame to which the pair of torsion bars are connected, and a mirror portion disposed inside the frame. The mirror portion is connected to the frame at each of a pair of first connection regions located on both sides of the mirror portion in a direction parallel to a second axis perpendicular to the first axis, and at each of a pair of second connection regions located on both sides of the mirror portion in a direction parallel to the first axis. Among the regions between the mirror portion and the frame, regions other than the pair of first connection regions and the pair of second connection regions are spaces. The outer edge of the mirror portion and the inner edge of the frame are connected so that the curvature is continuous at each of the pair of first connection regions when viewed from a direction perpendicular to the first axis and the second axis.

[0009] In this mirror device, a pair of torsion bars connected to the frame-shaped frame are disposed on the first axis, and a pair of first connection regions where the mirror portion and the frame-shaped frame are connected to each other are located on both sides of the mirror portion in a direction parallel to a second axis perpendicular to the first axis. Further, a pair of second connection regions where the mirror portion and the frame-shaped frame are connected to each other are located on both sides of the mirror portion in a direction parallel to the first axis. Thereby, even if the movable portion is swung at high speed, for example, compared to the case where only the pair of connection regions are located on the first axis, or the case where the mirror portion and the frame-shaped frame are connected to each other only in one connection region, the stress generated in each of the pair of first connection regions and each of the pair of second connection regions due to the torsion of the pair of torsion bars is reduced. Further, in this mirror device, the outer edge of the mirror portion and the inner edge of the frame are connected so that the curvature is continuous at each of the pair of first connection regions when viewed from a direction perpendicular to the first axis and the second axis. Thereby, stress concentration is less likely to occur at each of the pair of first connection regions. As described above, according to this mirror device, both bending of the mirror portion and breakage of the movable portion can be suppressed.

[0010] In the mirror device according to one aspect of the present disclosure, the outer edge of the mirror part and the inner edge of the frame may be connected such that the curvature is continuous in each of the pair of second connection regions when viewed from a direction perpendicular to the first axis and the second axis. Thereby, stress concentration is less likely to occur in each of the pair of second connection regions.

[0011] In the mirror device according to one aspect of the present disclosure, the pair of second connection regions may be located on both sides of the mirror part on the first axis. Thereby, the moment of inertia of the movable part around the first axis can be reduced.

[0012] In the mirror device according to one aspect of the present disclosure, the pair of first connection regions may be located on both sides of the mirror part on the second axis. Thereby, a sufficient distance (a distance at which the influence of the torsion of the pair of torsion bars hardly reaches each of the pair of first connection regions) can be secured between each of the pair of torsion bars and each of the pair of first connection regions. Therefore, while simplifying the configuration of the movable part, it is possible to suppress both the bending of the mirror part and the breakage of the movable part.

[0013] In the mirror device according to one aspect of the present disclosure, the frame includes a pair of first portions to which the mirror part is connected and which extend in a direction parallel to the first axis, and the width of each of the pair of first portions in the direction parallel to the second axis may become smaller as it is farther from each of the pair of first connection regions. Thereby, the stress generated due to the torsion of the pair of torsion bars can be dispersed to the portions where the width is smaller in each of the pair of first portions, and the stress generated in each of the pair of first connection regions can be made smaller. Further, while ensuring the connection strength at each of the pair of first connection regions, the moment of inertia of the movable part can be reduced by the amount by which the width is smaller in each of the pair of first portions. Reducing the moment of inertia of the movable part is advantageous for swinging the movable part at high speed.

[0014] In the mirror device according to one aspect of the present disclosure, the frame may further include a pair of second portions to which a pair of torsion bars are connected and which extend in a direction parallel to the second axis. Thereby, the stress generated due to the torsion of the pair of torsion bars is dispersed to the portion between the first portion and the second portion that are connected or joined to each other, and the stress generated in each of the pair of first connection regions can be made smaller.

[0015] In the mirror device according to one aspect of the present disclosure, the inner edge of each of the pair of first portions and the inner edge of each of the pair of second portions may be connected to each other such that the curvature is continuous in each of a plurality of regions where they are connected to each other when viewed from a direction perpendicular to the first axis and the second axis. Thereby, it is possible to suppress stress concentration from occurring in each of a plurality of regions where the inner edge of the first portion and the inner edge of the second portion are connected to each other.

[0016] In the mirror device according to one aspect of the present disclosure, the outer edge of each of the pair of first portions and the outer edge of each of the pair of second portions may be connected to each other such that the curvature is continuous in each of a plurality of regions where they are connected to each other when viewed from a direction perpendicular to the first axis and the second axis. Thereby, it is possible to suppress stress concentration from occurring in each of a plurality of regions where the outer edge of the first portion and the outer edge of the second portion are connected to each other.

[0017] In the mirror device according to one aspect of the present disclosure, the length of each of the pair of first portions in the direction parallel to the first axis may be longer than the length of each of the pair of second portions in the direction parallel to the second axis. Thereby, while suppressing an increase in the moment of inertia of the movable part, a sufficient distance (a distance at which the influence of the torsion of the pair of torsion bars hardly reaches each of the pair of first connection regions) can be ensured between each of the pair of torsion bars and each of the pair of first connection regions.

[0018] In the mirror device according to one aspect of the present disclosure, the distance between each of the pair of first connection regions and one of the pair of second portions, and the distance between each of the pair of first connection regions and the other of the pair of second portions may be longer than the distance between the first axis and each of the pair of first portions. Thereby, while suppressing an increase in the moment of inertia of the movable part, a sufficient distance (a distance at which it is difficult for the torsional influence of the pair of torsion bars to reach each of the pair of first connection regions) can be secured between each of the pair of torsion bars and each of the pair of first connection regions.

[0019] In the mirror device according to one aspect of the present disclosure, the shape of the mirror part when viewed from a direction perpendicular to the first axis and the second axis may be an ellipse having a major axis along the first axis. Thereby, while suppressing an increase in the moment of inertia of the movable part, a sufficient area of the mirror surface can be secured.

[0020] In the mirror device according to one aspect of the present disclosure, the width of each of the pair of first connection regions in the direction parallel to the first axis may be 30% or less of the width of the mirror part in the direction parallel to the first axis. Thereby, it is possible to achieve both ensuring sufficient connection strength between the mirror part and the frame and ensuring a sufficient distance between each of the pair of torsion bars and each of the pair of first connection regions.

Advantages of the Invention

[0021] According to the present disclosure, it is possible to provide a mirror device that can suppress both bending of the mirror part and breakage of the movable part.

Brief Description of the Drawings

[0022]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

[0023] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and redundant descriptions are omitted. [Configuration of Mirror Device]

[0024] As shown in FIG. 1, the mirror device 1 includes a base 2, a support portion 3, a movable portion 4, a pair of torsion bars 5 and 6, a pair of torsion bars 7 and 8, and a magnetic field generation portion 10. The base 2, the support portion 3, the movable portion 4, the pair of torsion bars 5 and 6, and the pair of torsion bars 7 and 8 are integrally formed by an SOI (Silicon on Insulator) substrate. That is, the mirror device 1 is configured as a MEMS device. The magnetic field generation portion 10 is configured by, for example, a permanent magnet having a Halbach array. In the mirror device 1, the movable portion 4 provided with the mirror portion 41 is swung about the X-axis (first axis) and the Y-axis (second axis perpendicular to the first axis), which are perpendicular to each other. The mirror device 1 is used, for example, in an optical switch for optical communication, an optical scanner, or the like.

[0025] The base 2 has an outer shape, for example, rectangular when viewed from a direction perpendicular to the X-axis and the Y-axis, and is formed in a frame shape. The base 2 is arranged on one side of the magnetic field generating unit 10. The support portion 3 has an outer shape, for example, octagonal when viewed from a direction perpendicular to the X-axis and the Y-axis, and is formed in a frame shape. The support portion 3 is arranged inside the base 2 in a state of being separated from the magnetic field generating unit 10. The movable portion 4 has an outer shape, for example, rectangular when viewed from a direction perpendicular to the X-axis and the Y-axis. The movable portion 4 is arranged inside the support portion 3 in a state of being separated from the magnetic field generating unit 10.

[0026] A pair of torsion bars 5, 6 are arranged on both sides of the support portion 3 on the Y-axis. The pair of torsion bars 5, 6 connect the support portion 3 to the base 2 so that the support portion 3 can swing about the Y-axis as the center line. Each torsion bar 5, 6 extends in a meandering shape for improving strength and facilitating adjustment of the torsional spring constant. A pair of torsion bars 7, 8 are arranged on both sides of the movable portion 4 on the X-axis. The pair of torsion bars 7, 8 connect the movable portion 4 to the support portion 3 so that the movable portion 4 can swing about the X-axis as the center line. Each torsion bar 7, 8 extends linearly along the X-axis.

[0027] The mirror device 1 further includes a coil 9, a coil 11, a plurality of wirings 12, 13, 14, 15, and a plurality of electrode pads 16, 17, 18, 19. The coil 9 is provided on the support portion 3. The coil 9 extends in a spiral shape, for example, in a state of being embedded in the support portion 3. The coil 11 is provided on the movable portion 4. The coil 9 extends in a spiral shape, for example, in a state of being embedded in the movable portion 4. Each of the coils 9, 11 is made of a metal material such as copper, for example. In the drawing, the regions where the coils 9, 11 are arranged are indicated by hatching.

[0028] The plurality of electrode pads 16, 17, 18, 19 are provided on the base 2. Each of the electrode pads 16, 17, 18, 19 is exposed to the outside from the insulating layer 21 on the base 2. The insulating layer 21 is integrally formed so as to cover the surfaces of the base 2, the support portion 3, the movable portion 4, the pair of torsion bars 5, 6 and the pair of torsion bars 7, 8 (the surfaces on the side opposite to the magnetic field generating portion 10). The insulating layer 21 is composed of, for example, a silicon dioxide film, a silicon nitride film, or the like.

[0029] The wiring 12 electrically connects one end of the coil 9 and the electrode pad 16. The wiring 12 extends from one end of the coil 9 through the torsion bar 5 to the electrode pad 16 while being embedded in the insulating layer 21. The wiring 13 electrically connects the other end of the coil 9 and the electrode pad 17. The wiring 13 extends from the other end of the coil 9 through the torsion bar 6 to the electrode pad 17 while being embedded in the insulating layer 21. Each of the wirings 12, 13 is composed of a metal material such as aluminum.

[0030] The wiring 14 electrically connects one end of the coil 11 and the electrode pad 18. The wiring 14 extends from one end of the coil 11 to the electrode pad 18 through the torsion bar 7, a part of the support portion 3, and the torsion bar 5 while being embedded in the insulating layer 21. The wiring 15 electrically connects the other end of the coil 11 and the electrode pad 19. The wiring 15 extends from the other end of the coil 11 to the electrode pad 19 through the torsion bar 8, a part of the support portion 3, and the torsion bar 6 while being embedded in the insulating layer 21. The portions of each of the wirings 14 and 15 passing through the respective torsion bars 7 and 8 are made of a metal material such as tungsten, for example, and the other portions are made of a metal material such as aluminum. As will be described later, since torsion occurs in the pair of torsion bars 7 and 8 due to the resonance of the movable portion 4 at the natural frequency, a larger load is applied to the portions of each of the wirings 14 and 15 passing through the respective torsion bars 7 and 8 than to the other portions. However, in the mirror device 1, since the portions of each of the wirings 14 and 15 passing through the respective torsion bars 7 and 8 are made of a metal material having a larger Vickers hardness than the other portions, metal fatigue hardly occurs in the wirings 14 and 15 on each of the torsion bars 7 and 8. In the drawings, the portions of each of the wirings 14 and 15 passing through the respective torsion bars 7 and 8 are indicated by hatching.

[0031] In the mirror device 1 configured as described above, when a drive signal for linear motion is input to the coil 9 via the electrode pads 16, 17 and the wirings 12, 13, a Lorentz force acts on the coil 9 due to the interaction with the magnetic field generated by the magnetic field generation unit 10. By utilizing the balance between the Lorentz force and the elastic forces of the pair of torsion bars 5, 6, the mirror unit 41 can be linearly moved together with the support unit 3 about the Y-axis as the center line. On the other hand, when a drive signal for resonant motion is input to the coil 11 via the electrode pads 18, 19 and the wirings 14, 15, a Lorentz force acts on the coil 11 due to the interaction with the magnetic field generated by the magnetic field generation unit 10. By utilizing the resonance of the movable part 4 at the natural frequency in addition to the Lorentz force, the mirror unit 41 can be resonantly moved about the X-axis as the center line. The natural frequency is determined by the moment of inertia of the movable part 4, the torsional spring constant of the pair of torsion bars 7, 8, etc. [Configuration of each part]

[0032] As shown in FIG. 2, the movable part 4 has a frame-shaped frame 42 in addition to the mirror part 41. A pair of torsion bars 7, 8 are connected to the frame 42. The mirror part 41 is disposed inside the frame 42. The mirror part 41 is connected to the frame 42 at each of a pair of connection regions (first connection regions) 40a, 40b located on both sides of the mirror part 41 in the direction parallel to the Y-axis (hereinafter referred to as the "Y-axis direction"). More specifically, the mirror part 41 is connected to the frame 42 at each of a pair of connection regions 40a, 40b located on both sides of the mirror part 41 on the Y-axis. The regions other than the pair of connection regions 40a, 40b in the region between the mirror part 41 and the frame 42 are spaces. That is, the mirror part 41 and the frame 42 are connected to each other only at the pair of connection regions 40a, 40b. The width (minimum width) W2 of each connection region 40a, 40b in the direction parallel to the X-axis (hereinafter referred to as the "X-axis direction") is 30% or less of the width (maximum width) W1 of the mirror part 41 in the X-axis direction.

[0033] When viewed from a direction perpendicular to the X-axis and the Y-axis, the shape of the mirror portion 41 is an ellipse having a major axis along the X-axis and a minor axis along the Y-axis, with the intersection O of the X-axis and the Y-axis as the center. On the surface of the mirror portion 41 (the surface opposite to the magnetic field generating portion 10), a mirror surface 41a is formed by a metal film made of, for example, aluminum or the like.

[0034] The frame 42 has an outer shape, for example, a rectangular shape when viewed from a direction perpendicular to the X-axis and the Y-axis, and is formed in a frame shape. More specifically, the frame 42 is formed in a frame shape by a pair of first portions 43, 44 extending in the X-axis direction and a pair of second portions 45, 46 extending in the Y-axis direction. The length of each of the first portions 43, 44 in the X-axis direction is longer than the length of each of the second portions 45, 46 in the Y-axis direction. Note that the length of each of the first portions 43, 44 in the X-axis direction can be regarded as the length of the outer edge or the inner edge of each of the first portions 43, 44 when viewed from a direction perpendicular to the X-axis and the Y-axis. The length of each of the second portions 45, 46 in the Y-axis direction can be regarded as the length of the outer edge or the inner edge of each of the second portions 45, 46 when viewed from a direction perpendicular to the X-axis and the Y-axis.

[0035] The distance between the connection region 40a and the second part 45, the distance between the connection region 40a and the second part 46, the distance between the connection region 40b and the second part 45, and the distance between the connection region 40b and the second part 46 are each longer than the distance between the X-axis and the first part 43 and the distance between the X-axis and the first part 44. Note that the distance between the connection region 40a and the second part 45 can be regarded as the distance (maximum distance) from the outer edge on the second part 45 side in the connection region 40a to the inner edge of the second part 45 along the X-axis direction. The distance between the connection region 40a and the second part 46 can be regarded as the distance (maximum distance) from the outer edge on the second part 46 side in the connection region 40a to the inner edge of the second part 46 along the X-axis direction. The distance between the connection region 40b and the second part 45 can be regarded as the distance (maximum distance) from the outer edge on the second part 45 side in the connection region 40b to the inner edge of the second part 45 along the X-axis direction. The distance between the connection region 40b and the second part 46 can be regarded as the distance (maximum distance) from the outer edge on the second part 46 side in the connection region 40b to the inner edge of the second part 46 along the X-axis direction. The distance between the X-axis and the first part 43 can be regarded as the distance (maximum distance) from the X-axis to the inner edge of the first part 43 along the Y-axis direction. The distance between the X-axis and the first part 44 can be regarded as the distance (maximum distance) from the X-axis to the inner edge of the first part 44 along the Y-axis direction.

[0036] The mirror part 41 is connected to the inner side (mirror part 41 side) side surface 43a of the first part 43 and the inner side (mirror part 41 side) side surface 44a of the first part 44. The torsion bar 7 is connected to the outer side (opposite side to the mirror part 41) side surface 45b of the second part 45. The torsion bar 8 is connected to the outer side (opposite side to the mirror part 41) side surface 46b of the second part 46.

[0037] The side surface 41b of the mirror part 41 and the inner side surface 43a of the first part 43 are connected in the connection region 40a such that the curvature is continuous. The side surface 41b of the mirror part 41 and the inner side surface 44a of the first part 44 are connected in the connection region 40b such that the curvature is continuous. That is, the outer edge of the mirror part 41 and the inner edge of the frame 42 are connected in the respective connection regions 40a and 40b such that the curvature is continuous when viewed from a direction perpendicular to the X-axis and the Y-axis. Note that "connected such that the curvature is continuous" means that there are no points where the curvature is discontinuous (for example, the vertices of sharp corners (including any of acute angles, right angles, and obtuse angles)). Therefore, if there are no points where the curvature is discontinuous, straight portions may be included in the outer edge of the mirror part 41 and the inner edge of the frame 42 in the respective connection regions 40a and 40b (the value of the curvature of the straight portion can be regarded as 0).

[0038] The width of the first part 43 in the Y-axis direction becomes smaller as it approaches the torsion bar 7 along the X-axis direction from the connection region 40a, and also becomes smaller as it approaches the torsion bar 8 along the X-axis direction from the connection region 40a. That is, the width of the first part 43 in the Y-axis direction becomes smaller as it moves away from the connection region 40a. Here, the outer side surface 43b (the side opposite to the mirror part 41) of the first part 43 is a flat surface parallel to the X-axis, and the inner side surface 43a of the first part 43 is a curved surface that is concave on the side opposite to the mirror part 41 so as to approach the side surface 43b as it moves away from the connection region 40a. The width of the first part 44 in the Y-axis direction becomes smaller as it approaches the torsion bar 7 along the X-axis direction from the connection region 40b, and also becomes smaller as it approaches the torsion bar 8 along the X-axis direction from the connection region 40b. That is, the width of the first part 44 in the Y-axis direction becomes smaller as it moves away from the connection region 40b. Here, the outer side surface 44b (the side opposite to the mirror part 41) of the first part 44 is a flat surface parallel to the X-axis, and the inner side surface 44a of the first part 44 is a curved surface that is concave on the side opposite to the mirror part 41 so as to approach the side surface 44b as it moves away from the connection region 40b.

[0039] The inner side surface 43a in the first part 43 and the inner side surface 45a (on the mirror part 41 side) in the second part 45 are connected to each other such that the curvature is continuous in the region where they are connected when viewed from a direction perpendicular to the X-axis and the Y-axis. The inner side surface 43a in the first part 43 and the inner side surface 46a (on the mirror part 41 side) in the second part 46 are connected to each other such that the curvature is continuous in the region where they are connected when viewed from a direction perpendicular to the X-axis and the Y-axis. The inner side surface 44a in the first part 44 and the inner side surface 45a in the second part 45 are connected to each other such that the curvature is continuous in the region where they are connected when viewed from a direction perpendicular to the X-axis and the Y-axis. The inner side surface 44a in the first part 44 and the inner side surface 46a in the second part 46 are connected to each other such that the curvature is continuous in the region where they are connected when viewed from a direction perpendicular to the X-axis and the Y-axis. That is, the inner edges of each of the first parts 43 and 44 and the inner edges of each of the second parts 45 and 46 are connected to each other such that the curvature is continuous in the regions where they are connected when viewed from a direction perpendicular to the X-axis and the Y-axis.

[0040] The outer side surface 43b in the first part 43 and the outer side surface 45b in the second part 45 are connected to each other such that the curvature is continuous in the region where they are connected when viewed from a direction perpendicular to the X-axis and the Y-axis. The outer side surface 43b in the first part 43 and the outer side surface 46b in the second part 46 are connected to each other such that the curvature is continuous in the region where they are connected when viewed from a direction perpendicular to the X-axis and the Y-axis. The outer side surface 44b in the first part 44 and the outer side surface 45b in the second part 45 are connected to each other such that the curvature is continuous in the region where they are connected when viewed from a direction perpendicular to the X-axis and the Y-axis. The outer side surface 44b in the first part 44 and the outer side surface 46b in the second part 46 are connected to each other such that the curvature is continuous in the region where they are connected when viewed from a direction perpendicular to the X-axis and the Y-axis. That is, the outer edges of each of the first parts 43 and 44 and the outer edges of each of the second parts 45 and 46 are connected to each other such that the curvature is continuous in the regions where they are connected when viewed from a direction perpendicular to the X-axis and the Y-axis.

[0041] In the second part 45, a slit 45c extending in the Y-axis direction is formed. When viewed from a direction perpendicular to the X-axis and the Y-axis, the slit 45c is located between the torsion bar 7 and the mirror part 41. In the second part 46, a slit 46c extending in the Y-axis direction is formed. When viewed from a direction perpendicular to the X-axis and the Y-axis, the slit 46c is located between the torsion bar 8 and the mirror part 41.

[0042] The coil 11 extends along the outer side surfaces 43b, 44b in each of the first parts 43, 44. The central position (the central position of the width in the Y-axis direction) of the region where the coil 11 extends in the first part 43 is located outside (on the side opposite to the connection region 40a) of the central position (the central position of the width in the Y-axis direction) of the first part 43. The central position (the central position of the width in the Y-axis direction) of the region where the coil 11 extends in the first part 44 is located outside (on the side opposite to the connection region 40b) of the central position (the central position of the width in the Y-axis direction) of the first part 44.

[0043] The coil 11 extends along the inner side surfaces 45a, 46a in each of the second parts 45, 46. The central position (the central position of the width in the X-axis direction) of the region where the coil 11 extends in the second part 45 is located inside (on the side opposite to the torsion bar 7) of the central position (the central position of the width in the X-axis direction) of the second part 45 (here, it is located inside the slit 45c). The central position (the central position of the width in the X-axis direction) of the region where the coil 11 extends in the second part 46 is located inside (on the side opposite to the torsion bar 8) of the central position (the central position of the width in the X-axis direction) of the second part 46 (here, it is located inside the slit 46c).

[0044] As shown in FIG. 3, both side surfaces 7a of the torsion bar 7 and the outer side surface 45b of the second portion 45 are connected to each other such that the curvature is continuous in each connected region when viewed from a direction perpendicular to the X-axis and the Y-axis. That is, the outer edge of the torsion bar 7 and the outer edge of the second portion 45 are connected to each other such that the curvature is continuous in each connected region when viewed from a direction perpendicular to the X-axis and the Y-axis. Both side surfaces 7a of the torsion bar 7 and the inner side surface 3a (on the side of the mirror portion 41) of the support portion 3 are connected to each other such that the curvature is continuous in each connected region when viewed from a direction perpendicular to the X-axis and the Y-axis. That is, the outer edge of the torsion bar 7 and the inner edge of the support portion 3 are connected to each other such that the curvature is continuous in each connected region when viewed from a direction perpendicular to the X-axis and the Y-axis. The curvature of the outer edge of the torsion bar 7 in the region connected to the outer edge of the second portion 45 is smaller than the curvature of the outer edge of the torsion bar 7 in the region connected to the inner edge of the support portion 3.

[0045] Similarly, both side surfaces of the torsion bar 8 and the outer side surface 46b of the second portion 46 are connected to each other such that the curvature is continuous in each connected region when viewed from a direction perpendicular to the X-axis and the Y-axis (see FIGS. 1 and 2). That is, the outer edge of the torsion bar 8 and the outer edge of the second portion 46 are connected to each other such that the curvature is continuous in each connected region when viewed from a direction perpendicular to the X-axis and the Y-axis. Both side surfaces of the torsion bar 8 and the inner side surface 3a of the support portion 3 are connected to each other such that the curvature is continuous in each connected region when viewed from a direction perpendicular to the X-axis and the Y-axis (see FIGS. 1 and 2). That is, the outer edge of the torsion bar 8 and the inner edge of the support portion 3 are connected to each other such that the curvature is continuous in each connected region when viewed from a direction perpendicular to the X-axis and the Y-axis. The curvature of the outer edge of the torsion bar 8 in the region connected to the outer edge of the second portion 46 is smaller than the curvature of the outer edge of the torsion bar 8 in the region connected to the inner edge of the support portion 3 (see FIGS. 1 and 2).

[0046] As shown in FIG. 3, the coil 9 extends along the side surface 3b on the outer side (opposite to the mirror portion 41) of the support portion 3. The central position (the central position of the width in the X-axis direction) of the region where the coil 9 extends in the portion of the support portion 3 to which the torsion bar 7 is connected is located outside (opposite to the torsion bar 7) the central position (the central position of the width in the X-axis direction) of the said portion. The central position (the central position of the width in the X-axis direction) of the region where the coil 9 extends in the portion of the support portion 3 to which the torsion bar 8 is connected is located outside (opposite to the torsion bar 8) the central position (the central position of the width in the X-axis direction) of the said portion (see FIGS. 1 and 2).

[0047] As shown in FIG. 4, a beam structure 31 is provided on the back surface (the surface on the magnetic field generating portion 10 side) of the support portion 3. The beam structure 31 extends annularly along the frame-shaped support portion 3 when viewed from a direction perpendicular to the X-axis and the Y-axis. The width (the width in the X-axis direction) of the portion of the beam structure 31 extending in the Y-axis direction is smaller than the width (the width in the Y-axis direction) of the portion of the beam structure 31 extending in the X-axis direction. In the portion of the beam structure 31 extending in the X-axis direction, a plurality of cutouts 31a are formed except for the intermediate portion crossing the Y-axis. The size of each cutout 31a increases as it is farther from the Y-axis.

[0048] The central position (the central position of the width in the X-axis direction) of the portion of the beam structure 31 extending in the Y-axis direction on the torsion bar 7 side is located outside (opposite to the torsion bar 7) the central position (the central position of the width in the X-axis direction) of the portion of the support portion 3 extending in the Y-axis direction and to which the torsion bar 7 is connected. The central position (the central position of the width in the X-axis direction) of the portion of the beam structure 31 extending in the Y-axis direction on the torsion bar 8 side is located outside (opposite to the torsion bar 8) the central position (the central position of the width in the X-axis direction) of the portion of the support portion 3 extending in the Y-axis direction and to which the torsion bar 8 is connected.

[0049] On the back surface of the mirror unit 41 (the surface on the magnetic field generating unit 10 side), a plurality of beam structures 47, 48, 49 are provided. When viewed from a direction perpendicular to the X-axis and Y-axis, the beam structure 47 extends in a V shape from the intersection point O toward both edge portions of the connection region 40a in the X-axis direction. When viewed from a direction perpendicular to the X-axis and Y-axis, the beam structure 48 extends in a V shape from the intersection point O toward both edge portions of the connection region 40b in the X-axis direction. When viewed from a direction perpendicular to the X-axis and Y-axis, the beam structure 49 extends in an X shape on both sides in the X-axis direction from the intersection point O. [Operation and Effect]

[0050] In the mirror device 1, a pair of torsion bars 7, 8 connected to the frame-shaped frame 42 are arranged on the X-axis, and a pair of connection regions 40a, 40b where the mirror unit 41 and the frame-shaped frame 42 are connected to each other are located on both sides of the mirror unit 41 in the Y-axis direction. Thereby, even if the movable part 4 is swung at high speed with the X-axis as the center line, for example, when only the pair of connection regions 40a, 40b are located on the X-axis, or when the mirror unit 41 and the frame-shaped frame 42 are connected to each other only in one connection region 40a (or 40b), compared with such cases, the stress generated in each of the connection regions 40a, 40b due to the torsion of the pair of torsion bars 7, 8 becomes smaller. Further, in the mirror device 1, the outer edge of the mirror unit 41 and the inner edge of the frame 42 are connected such that the curvature is continuous in each of the connection regions 40a, 40b when viewed from a direction perpendicular to the X-axis and Y-axis. Thereby, stress concentration hardly occurs in each of the connection regions 40a, 40b. As described above, according to the mirror device 1, it is possible to suppress both the bending of the mirror unit 41 and the breakage of the movable part 4.

[0051] In the mirror device 1, a pair of connection regions 40a and 40b are located on both sides of the mirror portion 41 on the Y-axis. Thereby, a sufficient distance (a distance at which it is difficult for the torsional influence of the pair of torsion bars 7 and 8 to reach the respective connection regions 40a and 40b) can be ensured between each torsion bar 7, 8 and each connection region 40a, 40b. Therefore, while simplifying the configuration of the movable part 4, it is possible to suppress both the bending of the mirror portion 41 and the breakage of the movable part 4.

[0052] In the mirror device 1, the frame 42 includes a pair of first portions 43 and 44 to which the mirror portion 41 is connected and which extend in the X-axis direction, and the width of each first portion 43, 44 in the Y-axis direction becomes smaller as it is farther from each connection region 40a, 40b. Thereby, the stress generated due to the torsion of the pair of torsion bars 7 and 8 can be dispersed to the portion where the width is smaller in each of the first portions 43 and 44, and the stress generated in each connection region 40a, 40b can be made smaller. Furthermore, while ensuring the connection strength at each connection region 40a, 40b, the moment of inertia of the movable part 4 when the X-axis is the rotation axis can be reduced by the amount by which the width is smaller in each of the first portions 43 and 44. Reducing the moment of inertia of the movable part 4 when the X-axis is the rotation axis is advantageous for swinging the movable part 4 at high speed with the X-axis as the center line. In particular, the inner side surface 43a of the first portion 43 is a curved surface that is concave on the side opposite to the mirror portion 41 so as to approach the outer side surface 43b of the first portion 43 as it is farther from the connection region 40a, and the inner side surface 44a of the first portion 44 is a curved surface that is concave on the side opposite to the mirror portion 41 so as to approach the outer side surface 44b of the first portion 44 as it is farther from the connection region 40b. Therefore, the stress generated due to the torsion of the pair of torsion bars 7 and 8 can be more reliably dispersed, and the occurrence of stress concentration in each of the first portions 43 and 44 can be suppressed.

[0053] (a) of FIG. 5 is a plan view of the movable part 4 of the comparative example, and (b) of FIG. 5 is a plan view of the movable part 4 (the above-described movable part 4) of the embodiment. (a) of FIG. 6 is a plan view of the movable part 4 of the comparative example, and (b) of FIG. 6 is a plan view of the movable part 4 of the embodiment. In the movable part 4 of the comparative example shown in (a) of FIG. 5, the widths of the respective first parts 43, 44 in the Y-axis direction are constant, and the width of the movable part 4 in the Y-axis direction is equal to the width in the movable part 4 of the embodiment shown in (b) of FIG. 5. In the movable part 4 of the comparative example shown in (a) of FIG. 6, the widths of the respective first parts 43, 44 in the Y-axis direction are constant, and the width of the movable part 4 in the Y-axis direction is smaller than the width in the movable part 4 of the embodiment shown in (b) of FIG. 6.

[0054] When comparing the movable part 4 of the comparative example shown in (a) of FIG. 5 with the movable part 4 of the comparative example shown in (a) of FIG. 6, in the movable part 4 of the comparative example shown in (a) of FIG. 5, the moment of inertia of the movable part 4 when the X-axis is the rotation axis becomes large, and in the movable part 4 of the comparative example shown in (a) of FIG. 6, the stress generated due to the torsion of the pair of torsion bars 7, 8 cannot be completely relaxed. On the other hand, according to the movable part 4 of the embodiment shown in (b) of FIG. 5 and (b) of FIG. 6, the moment of inertia of the movable part 4 when the X-axis is the rotation axis can be made smaller than that of the movable part 4 of the comparative example shown in (a) of FIG. 5. Further, according to the movable part 4 of the embodiment shown in (b) of FIG. 5 and (b) of FIG. 6, the stress generated due to the torsion of the pair of torsion bars 7, 8 can be relaxed compared to the movable part 4 of the comparative example shown in (a) of FIG. 6.

[0055] In the mirror device 1, the frame 42 includes, in addition to the pair of first parts 43, 44, a pair of second parts 45, 46 to which the pair of torsion bars 7, 8 are connected and which extend in the Y-axis direction. Thereby, the stress generated due to the torsion of the pair of torsion bars 7, 8 can be dispersed to the portions between the respective first parts 43, 44 and the respective second parts 45, 46 connected to each other, and the stress generated in each connection region 40a, 40b can be made smaller.

[0056] In the mirror device 1, the inner edges of the respective first portions 43 and 44 and the inner edges of the respective second portions 45 and 46 are connected to each other such that the curvature is continuous in the respective regions where they are connected when viewed from a direction perpendicular to the X-axis and the Y-axis. Thereby, it is possible to suppress the occurrence of stress concentration in the respective regions where the inner edges of the respective first portions 43 and 44 and the inner edges of the respective second portions 45 and 46 are connected to each other.

[0057] In the mirror device 1, the outer edges of the respective first portions 43 and 44 and the outer edges of the respective second portions 45 and 46 are connected to each other such that the curvature is continuous in the respective regions where they are connected when viewed from a direction perpendicular to the X-axis and the Y-axis. Thereby, it is possible to suppress the occurrence of stress concentration in the respective regions where the outer edges of the respective first portions 43 and 44 and the outer edges of the respective second portions 45 and 46 are connected to each other.

[0058] In the mirror device 1, the length of each of the first portions 43 and 44 in the X-axis direction is longer than the length of each of the second portions 45 and 46 in the Y-axis direction. Thereby, while suppressing an increase in the moment of inertia of the movable portion 4 when the X-axis is the rotation axis, a sufficient distance (a distance at which it is difficult for the torsional influence of the pair of torsion bars 7 and 8 to reach the respective connection regions 40a and 40b) can be ensured between each of the torsion bars 7 and 8 and each of the connection regions 40a and 40b.

[0059] In the mirror device 1, each of the distances between the connection region 40a and the second portion 45, between the connection region 40a and the second portion 46, between the connection region 40b and the second portion 45, and between the connection region 40b and the second portion 46 is longer than each of the distances between the X-axis and the first portion 43 and between the X-axis and the first portion 44. Thereby, while suppressing an increase in the moment of inertia of the movable portion 4 when the X-axis is the rotation axis, a sufficient distance (a distance at which it is difficult for the torsional influence of the pair of torsion bars 7 and 8 to reach the respective connection regions 40a and 40b) can be ensured between each of the torsion bars 7 and 8 and each of the connection regions 40a and 40b.

[0060] In the mirror device 1, the shape of the mirror part 41 when viewed from a direction perpendicular to the X-axis and the Y-axis is an ellipse having a major axis along the X-axis. Thereby, while suppressing an increase in the moment of inertia of the movable part 4 when the X-axis is the rotation axis, a sufficient area of the mirror surface 41a can be secured.

[0061] In the mirror device 1, the widths of the respective connection regions 40a and 40b in the X-axis direction are 30% or less of the width of the mirror part 41 in the X-axis direction. Thereby, it is possible to achieve both ensuring sufficient connection strength between the mirror part 41 and the frame 42 and ensuring a sufficient distance between each of the torsion bars 7 and 8 and each of the connection regions 40a and 40b.

[0062] In the mirror device 1, the coil 11 extends along the outer side surfaces 43b and 44b in each of the first parts 43 and 44, and extends along the inner side surfaces 45a and 46a in each of the second parts 45 and 46. As a result, since the coil 11 is separated from each of the connection regions 40a and 40b and each of the torsion bars 7 and 8, the stress generated in the coil 11 due to the torsion of the pair of torsion bars 7 and 8 is reduced. Therefore, it is possible to suppress the occurrence of metal fatigue in the coil 11. As described above, in each of the connection regions 40a and 40b, the stress is reduced to such an extent that it does not lead to bending of the mirror part 41 and breakage of the movable part 4, but there is a possibility that stress leading to metal fatigue of the coil 11 remains. Therefore, extending the coil 11 along the outer side surfaces 43b and 44b in each of the first parts 43 and 44 and separating the coil 11 from each of the connection regions 40a and 40b is effective from the viewpoint of safety.

[0063] In the mirror device 1, a slit 45c located between the torsion bar 7 and the mirror unit 41 is formed in the first portion 43, and a slit 46c located between the torsion bar 8 and the mirror unit 41 is formed in the first portion 44. Thereby, it becomes difficult for the twisting influence of the pair of torsion bars 7 and 8 to reach the coil 11. Therefore, it is possible to suppress the occurrence of metal fatigue in the coil 11. Further, it becomes difficult for the twisting influence of the pair of torsion bars 7 and 8 to reach the respective connection regions 40a and 40b. Therefore, both the bending of the mirror unit 41 and the breakage of the movable unit 4 can be more surely suppressed.

[0064] In the mirror device 1, the coil 9 extends along the outer side surface 3b of the support portion 3. Thereby, since the coil 9 is separated from the torsion bars 7 and 8, the stress generated in the coil 9 due to the twisting of the pair of torsion bars 7 and 8 is reduced. Therefore, it is possible to suppress the occurrence of metal fatigue in the coil 9.

[0065] In the mirror device 1, the curvature of the outer edge of the torsion bar 7 in the region connected to the outer edge of the second portion 45 is smaller than the curvature of the outer edge of the torsion bar 7 in the region connected to the inner edge of the support portion 3. Similarly, the curvature of the outer edge of the torsion bar 8 in the region connected to the outer edge of the second portion 46 is smaller than the curvature of the outer edge of the torsion bar 8 in the region connected to the inner edge of the support portion 3. By reducing the curvature of the outer edges of the torsion bars 7 and 8 in the region connected to the frame 42, the stress generated in the frame 42 due to the twisting of the pair of torsion bars 7 and 8 can be reduced. On the other hand, by increasing the curvature of the outer edges of the torsion bars 7 and 8 in the region connected to the support portion 3, the lengths of the torsion bars 7 and 8 can be ensured, and the stress itself generated due to the twisting of the pair of torsion bars 7 and 8 can be reduced. Note that it is more effective to reduce the stress generated due to the twisting of the pair of torsion bars 7 and 8 on the side of the movable unit 4 that can be linearly operated rather than on the side of the support portion 3.

[0066] In the mirror device 1, a beam structure 31 that extends annularly along the frame-shaped support portion 3 is provided on the back surface of the support portion 3. Thereby, deformation of the support portion 3 can be suppressed. Moreover, since the beam structure 31 is formed continuously, stress concentration can be suppressed compared to the case where the beam structure 31 is formed intermittently. Further, in the mirror device 1, the width (width in the X-axis direction) of the portion of the beam structure 31 that extends in the Y-axis direction is smaller than the width (width in the Y-axis direction) of the portion of the beam structure 31 that extends in the X-axis direction. Thereby, the moment of inertia of the support portion 3 when the Y-axis is the rotation axis can be reduced. Also, in the mirror device 1, the size of each cutout 31a formed in the portion of the beam structure 31 that extends in the X-axis direction increases as it moves away from the Y-axis. Thereby, the moment of inertia of the support portion 3 when the Y-axis is the rotation axis can be reduced. Further, in the mirror device 1, no cutout 31a is formed in the intermediate portion of the beam structure 31 that crosses the Y-axis. Thereby, the moment of inertia of the support portion 3 when the X-axis is the rotation axis can be increased, and rocking of the support portion 3 about the X-axis can be suppressed. Furthermore, in the mirror device 1, the central position of the portion of the beam structure 31 that extends in the Y-axis direction is located outside the central position of the portion of the support portion 3 that extends in the Y-axis direction. Thereby, the portion of the beam structure 31 that extends in the Y-axis direction on the torsion bar 7 side is separated from the torsion bar 7, and the portion of the beam structure 31 that extends in the Y-axis direction on the torsion bar 8 side is separated from the torsion bar 8. Therefore, the stress generated in the beam structure 31 due to the torsion of the pair of torsion bars 7 and 8 can be reduced.

[0067] In the mirror device 1, a beam structure 47 that extends in a V shape from the intersection point O toward both edge portions of the connection region 40a in the X-axis direction and a beam structure 48 that extends in a V shape from the intersection point O toward both edge portions of the connection region 40b in the X-axis direction are provided on the back surface of the mirror portion 41. Thereby, the stress generated in each connection region 40a, 40b due to the torsion of the pair of torsion bars 7, 8 can be reduced. [Modification Example]

[0068] The present disclosure is not limited to the above-described embodiments. For example, the materials and shapes of each part are not limited to the above-described materials and shapes, and various materials and shapes can be adopted. As an example, if the frame 42 is formed in a frame shape, it may have an outer shape such as a polygonal shape other than a quadrilateral when viewed from a direction perpendicular to the X-axis and the Y-axis. Further, the mirror surface 41a may be formed on at least a part of the mirror part 41. Further, the shape of the mirror part 41 when viewed from a direction perpendicular to the X-axis and the Y-axis may be a circular shape or the like. Further, the driving method of the mirror device 1 is not limited to the electromagnetic driving method, and may be an electrostatic driving method, a piezoelectric driving method, a thermal driving method, or the like. Further, the base 2 and the pair of torsion bars 5 and 6 are not provided in the mirror device 1, and the support part 3 may function as a base.

[0069] Further, when the pair of torsion bars 7 and 8 are arranged on both sides of the movable part 4 on the first axis, the pair of connection regions 40a and 40b may be located on both sides of the mirror part 41 in a direction parallel to the second axis perpendicular to the first axis. As an example, when a pair of portions (portions constituting opposite sides) of the frame 42 formed in a polygonal frame shape intersect the second axis, the pair of connection regions 40a and 40b may be arranged within the pair of portions. In the above-described embodiment, the pair of connection regions 40a and 40b may be arranged within the pair of first portions 43 and 44. Alternatively, regardless of the shape of the frame 42, the pair of connection regions 40a and 40b may be arranged in a region of 45 degrees or more and 135 degrees or less in one direction from the first axis and a region of 45 degrees or more and 135 degrees or less in the other direction from the first axis with the intersection point of the first axis and the second axis as the center point. Note that each of the connection regions 40a and 40b may be constituted by a plurality of physically separated regions.

[0070] Further, if the width of the first portion 43 in the Y-axis direction becomes smaller as it moves away from the connection region 40a, as shown in FIG. 7(a), the inner side surface 43a of the first portion 43 may be a flat surface inclined so as to approach the outer side surface 43b of the first portion 43 as it moves away from the connection region 40a. Similarly, if the width of the first portion 44 in the Y-axis direction becomes smaller as it moves away from the connection region 40b, as shown in FIG. 7(a), the inner side surface 44a of the first portion 44 may be a flat surface inclined so as to approach the outer side surface 44b of the first portion 44 as it moves away from the connection region 40b.

[0071] Further, if the width of the first portion 43 in the Y-axis direction becomes smaller as it moves away from the connection region 40a, as shown in FIG. 7(b), the inner side surface 43a of the first portion 43 may be a curved surface bent in a stepped manner so as to approach the outer side surface 43b of the first portion 43 as it moves away from the connection region 40a. Similarly, if the width of the first portion 44 in the Y-axis direction becomes smaller as it moves away from the connection region 40b, as shown in FIG. 7(b), the inner side surface 44a of the first portion 44 may be a curved surface bent in a stepped manner so as to approach the outer side surface 44b of the first portion 44 as it moves away from the connection region 40b.

[0072] Also, in the movable portion 4 of the third modification, as shown in FIG. 8, the mirror portion 41 is connected to the frame 42 at each of a pair of connection regions (first connection regions) 40a and 40b located on both sides of the mirror portion 41 in the Y-axis direction, and at each of a pair of connection regions (second connection regions) 40c and 40d located on both sides of the mirror portion 41 in the X-axis direction. The regions other than the pair of connection regions 40a and 40b and the pair of connection regions 40c and 40d in the region between the mirror portion 41 and the frame 42 are spaces. That is, the mirror portion 41 and the frame 42 are connected to each other only at the pair of connection regions 40a and 40b and the pair of connection regions 40c and 40d.

[0073] The side surface 41b of the mirror part 41 and the inner side surface 43a of the first part 43 are connected in the connection region 40a such that the curvature is continuous. The side surface 41b of the mirror part 41 and the inner side surface 44a of the first part 44 are connected in the connection region 40b such that the curvature is continuous. That is, the outer edge of the mirror part 41 and the inner edge of the frame 42 are connected in the respective connection regions 40a, 40b such that the curvature is continuous when viewed from a direction perpendicular to the X-axis and the Y-axis.

[0074] The side surface 41b of the mirror part 41 and the inner side surface 45a of the second part 45 are connected in the connection region 40d such that the curvature is continuous. The side surface 41b of the mirror part 41 and the inner side surface 46a of the second part 46 are connected in the connection region 40c such that the curvature is continuous. That is, the outer edge of the mirror part 41 and the inner edge of the frame 42 are connected in the respective connection regions 40c, 40d such that the curvature is continuous when viewed from a direction perpendicular to the X-axis and the Y-axis.

[0075] The width of the first part 43 in the Y-axis direction decreases as it moves away from the connection region 40a. Here, the outer side surface 43b of the first part 43 is a flat surface parallel to the X-axis, and the inner side surface 43a of the first part 43 is a surface that approaches the side surface 43b as it moves away from the connection region 40a. The width of the first part 44 in the Y-axis direction decreases as it moves away from the connection region 40b. Here, the outer side surface 44b of the first part 44 is a flat surface parallel to the X-axis, and the inner side surface 44a of the first part 44 is a surface that approaches the side surface 44b as it moves away from the connection region 40b.

[0076] Note that the inner side surface 43a in the first portion 43 may be a flat surface inclined so as to approach the outer side surface 43b in the first portion 43 as it moves away from the connection region 40a. Similarly, the inner side surface 44a in the first portion 44 may be a flat surface inclined so as to approach the outer side surface 44b in the first portion 44 as it moves away from the connection region 40b. Further, the inner side surface 43a in the first portion 43 may be a curved surface bent in a stepped manner so as to approach the outer side surface 43b in the first portion 43 as it moves away from the connection region 40a. Similarly, the inner side surface 44a in the first portion 44 may be a curved surface bent in a stepped manner so as to approach the outer side surface 44b in the first portion 44 as it moves away from the connection region 40b.

[0077] The width of the second portion 45 in the X-axis direction becomes smaller as it moves away from the connection region 40d. Here, the outer side surface 45b in the second portion 45 is a flat surface parallel to the Y-axis, and the inner side surface 45a in the second portion 45 is a surface that approaches the side surface 45b as it moves away from the connection region 40d. The width of the second portion 46 in the X-axis direction becomes smaller as it moves away from the connection region 40c. Here, the outer side surface 46b in the second portion 46 is a flat surface parallel to the Y-axis, and the inner side surface 46a in the second portion 46 is a surface that approaches the side surface 46b as it moves away from the connection region 40c.

[0078] Note that the inner side surface 45a in the second portion 45 may be a flat surface inclined so as to approach the outer side surface 45b in the second portion 45 as it moves away from the connection region 40d. Similarly, the inner side surface 46a in the second portion 46 may be a flat surface inclined so as to approach the outer side surface 46b in the second portion 46 as it moves away from the connection region 40c. Further, the inner side surface 45a in the second portion 45 may be a curved surface bent in a stepped manner so as to approach the outer side surface 45b in the second portion 45 as it moves away from the connection region 40d. Similarly, the inner side surface 46a in the second portion 46 may be a curved surface bent in a stepped manner so as to approach the outer side surface 46b in the second portion 46 as it moves away from the connection region 40c.

[0079] In the mirror device 1 including the movable part 4 of the third modification example, a pair of torsion bars 7 and 8 connected to the frame-shaped frame 42 are arranged on the X axis, and a pair of connection regions 40a and 40b where the mirror part 41 and the frame-shaped frame 42 are connected to each other are located on both sides of the mirror part 41 in the Y-axis direction. Further, a pair of connection regions 40c and 40d where the mirror part 41 and the frame-shaped frame 42 are connected to each other are located on both sides of the mirror part 41 in the X-axis direction. Thereby, even if the movable part 4 is swung at high speed about the X axis, for example, when only the pair of connection regions 40a and 40b are located on the X axis, or when the mirror part 41 and the frame-shaped frame 42 are connected to each other only in one connection region 40a (or 40b), etc., the stress generated in each of the connection regions 40a, 40b, 40c, and 40d due to the torsion of the pair of torsion bars 7 and 8 becomes smaller. Further, in the mirror device 1 including the movable part 4 of the third modification example, the outer edge of the mirror part 41 and the inner edge of the frame 42 are connected so that the curvature is continuous in each of the connection regions 40a and 40b when viewed from a direction perpendicular to the X axis and the Y axis. Thereby, it becomes difficult for stress concentration to occur in each of the connection regions 40a and 40b. As described above, according to the mirror device 1 including the movable part 4 of the third modification example, both the bending of the mirror part 41 and the breakage of the movable part 4 can be suppressed.

[0080] In the mirror device 1 including the movable part 4 of the third modification example, the outer edge of the mirror part 41 and the inner edge of the frame 42 are connected so that the curvature is continuous in each of the connection regions 40c and 40d when viewed from a direction perpendicular to the X axis and the Y axis. Thereby, it becomes difficult for stress concentration to occur in each of the connection regions 40c and 40d.

[0081] In the mirror device 1 including the movable part 4 of the third modification example, a pair of connection regions 40c and 40d are located on both sides of the mirror part 41 on the X axis. Thereby, the moment of inertia of the movable part around the X axis can be reduced.

[0082] When a pair of torsion bars 7 and 8 are arranged on both sides of the movable part 4 on the first axis, the pair of connection regions 40c and 40d may be located on both sides of the mirror part 41 in a direction parallel to the first axis. As an example, when a pair of portions (portions constituting opposite sides) of the frame 42 formed in a polygonal frame shape intersect the first axis, the pair of connection regions 40c and 40d may be arranged in the pair of portions. For the movable part 4 of the third modification example, the pair of connection regions 40c and 40d may be arranged in the pair of second portions 45 and 46. Alternatively, regardless of the shape of the frame 42, a region of 45 degrees or more and 135 degrees or less in one direction from the second axis and a region of 45 degrees or more and 135 degrees or less in the other direction from the second axis with the intersection point of the first axis and the second axis as the center point, the pair of connection regions 40c and 40d may be arranged. Each connection region 40c and 40d may be composed of a plurality of physically separated regions.

[0083] In the mirror device 1 including the movable part 4 of the third modification example, the widths of the respective first portions 43 and 44 in the Y-axis direction become smaller as they are farther from the respective connection regions 40a and 40b, and the widths of the respective second portions 45 and 46 in the X-axis direction become smaller as they are farther from the respective connection regions 40c and 40d. Thereby, the stress generated due to the torsion of the pair of torsion bars 7 and 8 is dispersed to the portions where the widths are smaller in the respective first portions 43 and 44 and the respective second portions 45 and 46, and the stress generated in the respective connection regions 40a, 40b, 40c, and 40d can be made smaller. Furthermore, while ensuring the connection strength at each of the connection regions 40a, 40b, 40c, and 40d, the moment of inertia of the movable part 4 when the X-axis is the rotation axis can be reduced by the amount by which the widths are smaller in the respective first portions 43 and 44 and the respective second portions 45 and 46. However, the widths of the respective second portions 45 and 46 in the X-axis direction do not necessarily have to become smaller as they are farther from the respective connection regions 40c and 40d.

[0084] In the mirror device 1 including the movable part 4 of the third modification, a slit 45c located between the torsion bar 7 and the mirror part 41 is formed in the first part 43, and a slit 46c located between the torsion bar 8 and the mirror part 41 is formed in the first part 44. Further, the curvature of the outer edge of the torsion bar 7 in the region connected to the outer edge of the second part 45 is smaller than the curvature of the outer edge of the torsion bar 7 in the region connected to the inner edge of the support part 3. Similarly, the curvature of the outer edge of the torsion bar 8 in the region connected to the outer edge of the second part 46 is smaller than the curvature of the outer edge of the torsion bar 8 in the region connected to the inner edge of the support part 3. As a result, in the mirror device 1 including the movable part 4 of the third modification, stable support of the mirror part 41 is achieved by the four connection regions 40a, 40b, 40c, 40d, while it becomes difficult for the influence of the twist of the pair of torsion bars 7, 8 to reach the pair of connection regions 40c, 40d.

[0085] Each configuration in the above-described embodiment is also applicable to the mirror device 1 including the movable part 4 of the third modification. For example, the inner edges of each of the first parts 43 and 44 and the inner edges of each of the second parts 45 and 46 are connected to each other such that the curvature is continuous in each region where they are connected when viewed from a direction perpendicular to the X-axis and the Y-axis. Also, the outer edges of each of the first parts 43 and 44 and the outer edges of each of the second parts 45 and 46 are connected to each other such that the curvature is continuous in each region where they are connected when viewed from a direction perpendicular to the X-axis and the Y-axis. Also, the length of each of the first parts 43 and 44 in the X-axis direction is longer than the length of each of the second parts 45 and 46 in the Y-axis direction. Also, each of the distances between the connection region 40a and the second part 45, the connection region 40a and the second part 46, the connection region 40b and the second part 45, and the connection region 40b and the second part 46 is longer than each of the distances between the X-axis and the first part 43 and the X-axis and the first part 44. Also, the shape of the mirror part 41 when viewed from a direction perpendicular to the X-axis and the Y-axis is an ellipse having a major axis along the X-axis. Also, the width of each of the connection regions 40a and 40b in the X-axis direction is 30% or less of the width of the mirror part 41 in the X-axis direction. Also, the coil 11 extends along the outer side surfaces 43b and 44b in each of the first parts 43 and 44, and extends along the inner side surfaces 45a and 46a in each of the second parts 45 and 46. Also, the coil 9 extends along the outer side surface 3b of the support part 3. Also, a beam structure 31 that extends annularly along the frame-shaped support part 3 is provided on the back surface of the support part 3. Also, on the back surface of the mirror part 41, a beam structure 47 that extends in a V shape from the intersection point O toward both edge portions of the connection region 40a in the X-axis direction and a beam structure 48 that extends in a V shape from the intersection point O toward both edge portions of the connection region 40b in the X-axis direction are provided.

[0086] Even in the mirror device 1 including the movable part 4 of the third modification example, the materials and shapes of the respective parts are not limited to the materials and shapes described above, and various materials and shapes can be adopted. As an example, if the frame 42 is formed in a frame shape, it may have an outer shape such as a polygon other than a quadrilateral when viewed from a direction perpendicular to the X-axis and the Y-axis. Further, the mirror surface 41a only needs to be formed in at least a part of the mirror part 41. Further, the shape of the mirror part 41 when viewed from a direction perpendicular to the X-axis and the Y-axis may be a circular shape or the like.

[0087] In the above-described embodiments and each modification example, the coil 11 for swinging the movable part 4 is provided in the movable part 4, and the coil 9 for swinging the support part 3 is provided in the support part 3. However, the coil for swinging the movable part 4 and the coil for swinging the support part 3 may be provided in the support part 3 respectively, or a single coil for swinging the movable part 4 and swinging the support part 3 may be provided in the support part 3.

[0088] Each configuration in the above-described one embodiment or modification example can be arbitrarily applied to each configuration in other embodiments or modification examples.

Explanation of Reference Numerals

[0089] 1... mirror device, 3... support part, 4... movable part, 7, 8... torsion bars, 40a, 40b... connection regions (first connection regions), 40c, 40d... connection regions (second connection regions), 41... mirror part, 42... frame, 43, 44... first parts, 45, 46... second parts.

Claims

1. A base, a frame-shaped support portion, a movable portion on which a mirror surface is formed, a first torsion bar that connects the movable portion to the support portion so that the movable portion can swing about a first axis as a center line, a second torsion bar that connects the support portion to the base so that the support portion can swing about a second axis as a center line, and a first beam structure is provided on the support portion, the first beam structure is formed at a portion of the support portion connected to the first torsion bar, and has a first portion extending in a direction along the second axis, and is formed at a portion of the support portion connected to the second torsion bar, and has a second portion extending in a direction along the first axis, a mirror device, wherein a width of the first portion in the direction along the first axis is smaller than a width of the second portion in the direction along the second axis.

2. The mirror device according to claim 1, wherein the first beam structure extends annularly along the frame-shaped support portion.

3. The mirror device according to claim 2, wherein a curvature of an inner edge of the first beam structure extending annularly is continuous when viewed from a direction perpendicular to both the first axis and the second axis.

4. The mirror device according to claim 2 or 3, wherein a shape of an outer edge of the first beam structure extending annularly is an octagonal shape when viewed from a direction perpendicular to both the first axis and the second axis.

5. The mirror device according to any one of claims 1 to 4, wherein a cutout is formed in the first beam structure.

6. The mirror surface is formed on one surface of the movable portion, The mirror device according to any one of claims 1 to 5, wherein the first beam structure is provided on a back surface of the support portion opposite to the one side.

7. A central position of the first portion is located outside a central position of the portion of the support portion connected to the first torsion bar, The central position of the first portion is a central position of a width in the direction along the first axis, The mirror device according to any one of claims 1 to 6, wherein the central position of the portion of the support portion connected to the first torsion bar is a central position of a width in the direction along the first axis.

8. The mirror device according to any one of claims 1 to 7, wherein a second beam structure is provided on the movable portion.

9. The movable part has a frame-shaped frame to which the first torsion bar is connected, and a mirror part disposed inside the frame. The mirror surface is formed on one surface of the mirror part, and the second beam structure is provided on the back surface of the mirror part on the side opposite to the one side. The mirror device according to claim 8.

10. The width of the end of the first torsion bar on the support part side is larger as it approaches the support part when viewed from a direction perpendicular to both the first axis and the second axis. The mirror device according to any one of claims 1 to 9.

11. The width of the end of the first torsion bar on the movable part side is larger as it approaches the movable part when viewed from a direction perpendicular to both the first axis and the second axis. The mirror device according to any one of claims 1 to 10.

12. The second torsion bar extends in a meandering shape. The mirror device according to any one of claims 1 to 11.

13. The base, the support part, the movable part, the first torsion bar, and the second torsion bar are integrally formed by a semiconductor substrate. The mirror device according to any one of claims 1 to 12.

14. The first torsion bar is each of a pair of first torsion bars disposed on both sides of the movable part on the first axis. The second torsion bar is each of a pair of second torsion bars disposed on both sides of the support part on the second axis. The mirror device according to any one of claims 1 to 13.

15. The first part is each of a pair of first parts formed at a part of the support part connected to the pair of first torsion bars. The second part is each of a pair of second parts formed at a part of the support part connected to the pair of second torsion bars. The width of each of the pair of first parts in the direction along the first axis is smaller than the width of each of the pair of second parts in the direction along the second axis. The mirror device according to claim 14.

16. The first beam structure further has a third part connected to the end of the first part. The mirror device according to any one of claims 1 to 15, wherein the third portion extends from the end portion of the first portion toward the second axis along a direction intersecting both the direction along the first axis and the direction along the second axis when viewed from a direction perpendicular to both the first axis and the second axis.

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